Mercury switch



D86. 5, 1933. p |AMBLET 1,937,746

MERCURY SWITCH Filed April 28. 1928 IE Z INVENTOR. I

BY a mqw A TTORNEY.

Patented Dec. 5, 1933 UNITED STATES PATENT OFFICE MERCURY SWITCH Paul K.Cramblet, Milwaukee, Wis., assignor, by mesne assignments, toMinneapolis-Honeywell Regulator Company, Minneapolis, Minn a cor- 1Claim.

This invention relates generally to circuit; makers and breakers andmore particularly to a switch of the type having a hermetically sealedand evacuated or gas filled container which houses the operatingelements of the switch.

One of the objects of the invention is to provide a switch of this typehaving a flexible or expansible and contractible element,suchasabellows, an elastic or flexible diaphragm or a flexible diskincorporated in the structure of the container and operable to cause theswitch to make and break an electric circuit. Such a flexible element,being susceptible of convenient operation in a variety of ways, may beresponsive to a fluid pressure control or to the operation and controlof mechanical operating mechanism, and is utilized to actuate or controlthe operation of the contact making and breaking elements of the switch.In a mercury switch, these contact making and breaking elements may beso constructed and so organized with the flexible element as to providea mercury to mercury make and break, or a make and break between a bodyof mercury and a movable electrode connected with and actuated by orthrough the flexible element. This organization has the advantage ofpermitting the container to remain stationary, if desired, and yet theswitch may be operated at the desired speed and may be made extremelysensitive and accurate in its operation.

In one embodiment of the present invention a mercury switch is providedwhich comprises an outer container made up of a glass envelope having anopening and a flexible element, for example a bellows having a sleeve orflange fused and sealed to the glass envelope around the margin of itsopening. Within the container circuit making and breaking means isprovided and includes a body of mercury in constant electricalconnection with one side of the circuit either through an electrodesealed in through the glass envelope or through a metal cap fused andsealed to the glass envelope and in constant contact with the body ofmercury or otherwise. A movable electrode of the rod or solid type iscarried by the bellows or other flexible element and is positivelyactuated or controlled thereby. This movable electrode is also inconstant electrical connection with the opposite side of the circuiteither through the bellows on which it is carried or otherwise. Themovable electrode may be made to make and break contact with the body ofmercury when actuated by the flexible element or may carry a trap or cupcontaining a body of mercury which makes and breaks with the stationarybody of mercury under the control of the bellows. The flexible elementis susceptible of operation and control in any number of different ways.For instance, either fluid pressure or mechanic 1 means may be utilizedto control the expansion and contraction of the bellows, or the flexionof the flexibleelement and such movement or flexion of the bellows orother flexible element is utilized to actuate the contact making andbreaking elements of the switch. The flexible element operates to causethe actuation of the contact making and breaking elements of the switchpositively for both the making and the breaking operations as it ispositively connected to the movable electrode.

Other objects and advantages reside in certain novel features of theconstruction, arrangement and combination of parts which will behereinafter more fully described and particularly pointed out in theappended claim, reference being had to the accompanying drawing forminga part of this specification, and in which:

Figure 1 is a view partly in section and partly in elevation showing oneform of mercury switch embodying the present invention;

Figure 2 is a similar view showing a somewhat diflerent form of switch;and

Figure 3 is a similar view showing still another form of switch.

Referring to the drawing, and more particularly to Figure 1, it will beseen that in the embodiment of the invention shown the switch comprisesan hermetically sealed container made up of a glass envelope 1 havingone end closed as at 2 and having its other end provided with an opening3. The envelope 1 may be 01' any suitable glass composition. A flexibleelement which may be a bellows 4 is provided and may be made of copper,nickel, Monel-metal, or of any other material having the propertiesmaking its suitable for this use. Preferably the metal of which thebellows is constituted is substantially unaffected by mercury or has acoating of metal unaffected by the action of mercury. In addition, themetal utilized or its coating should be non-porous as the container" isevacuated to a commercial vacuum and filled with an inert arcsuppressing gas. Nickel rolled in vacuum is one example of such anon-porous metal. The bellows 4 has an integral flange 5 fitted in andwelded or otherwise secured to one end of a sleeve 6 constituted of thesame metal as the bellows and having its opposite end fitted over theopen end 3 of the glass envelope or tube 1, and fused and sealedthereto. This fusion and sealing is accomplished by heating the sleeveand consequently also the interfltted portion of the envelope 1 untilthe glass making up the envelope is in a somewhat plastic state. Duringthis heating action the sleeve 6 and the envelope 1 are rotated so thatthe plastic end of the envelope is displaced into intimate contact withthe inner surface of the sleeve and becomes fused and sealed thereto toprovide a permanent mechanical connection as well as a seal over asubstantial area between these parts. This method of uniting theenvelope 1 with the metal sleeve is fully set forth, described andclaimed in the co-pending application of Clifford Hotchkiss, fliedJanuary I, 1928, Serial No. 245,238, to which reference is made for afulldisclosure of this method. It is obvious that the sleeve 6 insteadof being a separate element may be formed integrally with the bellows.

An electrode 10 is sealed in through the closed end 2 of the glassenvelope 1 and is immersed in a body of mercury designated at 11. Amovable electrode 12 of the rod or solid type is soldered, welded, orotherwise appropriately secured as at 13 to the end plate of the bellows4 and this movable electrode projects into the glass envelope 1 and isoperatively related to the body of mercury 11. The movable electrode 12is characterizedas of the rod or solid type in the sense trode. A smallbody of mercury designated at 16 is contained in thetrap 14.

It is to be understood that the trap 14 may be omitted and, in suchevent, the movable electrode has direct contact with the body of mercury11 in the closed position of the switch. 1

In the form of the invention shown in Figure 1 the bellows 4 is housedin a pressure chamber 20 having a pipe 21 which leads to any source ofvariable fluid pressure or control means which of itself forms no partof the present invention. In the chamber 20 the pressure rises and fallsto cause expansion and contraction of the bellows. When the bellows iscompressed or contracted, electrode 12 is moved downwardly and the trap14 is lowered down into the body of mercury 11 so that this body ofmercury 11 unites with the body of mercury 16 over the lip of the trap14. Upon lowering of the pressure in the chamber 20 the inherentresiliency of the bellows 4 and the gas pressure previously set up inthe switch by the contraction of the bellows causes it to expand therebyraising the electrode 12 and its trap 14 to cause the body of mercury 16to separate from the body of mercury 11 over the lip of the trap therebybreaking the electrical circuit in which the switch is incorporated;Thus, the electrode 12 is positively moved in both directions. It is tobe understood that one side of the circuit is connected to the electrode10 and the other side is connected to the electrode 12 through thesleeve 6 or through the bellows.

While this and the other forms of the invention illustrated contemplatesespecially metal to mercury or mercury to mercury contact, the inventionis not restricted to these types of contact making and breaking meansbut may utilize any types of contacts such as metal to metal contact orcontacts of other conductive materials. Whatever may be the character ofthe contacts, the advantages of the hermetically sealed container and ofthe flexible operating member incorporated therein are always realized.

The switch shown in Figure 2 has an hermetically sealed containerincluding a glass envelope 1 similar in construction to the glassenvelope 1 but horizontally disposed in its operative position andprovided with a well 2' containing a body of mercury 11 into which anelectrode 10' projects. A flexible element which may be a bellows 4 isprovided and is of the same construction as the bellows 4 and has a gastight connection with the glass envelope 1 as by means of a sleeve 6welded to the flange of the bellows and fused and sealed to the glassenvelope, as in the form of the invention shown in Figure 1. The switchof Figure 2 also has a movable electrode 12* soldered or welded to thebellows and carrying a trap 14* in which a body of mercury 16* iscontained. The trap 14' may be omitted so that the electrode 12- willmake and break contact with the body of mercury 11, if thus desired. Inthis form of the invention the electrode 12' is rocked to cause thebodies of mercury 11'- and 16' to unite and separate to make and breakthe circuit in which the switch is incorporated. This rocking of theelectrode 12' may be accomplished in any suitable manner. One means forrocking the electrode 12 is illustrated diagrammatically in Figure 2,and may consist of an arm 25 formed as an extension of the electrode butlocated exteriorly of the container and also appropriately insulatedfrom the electrode as indicated at 26. The outer end of the arm 25 has asuitable connection 27 to a connecting rod 28 secured to an eccentricstrap 29 embracing an eccentric 30 mounted on a drive shaft 31. As thedrive shaft 31 is turned the connecting rod 28 arises and lowers to rockthe arm 25 and consequently also to rock the electrode 12, the bellows4' permitting this operation.

The switch shown in Figure 3 is very similar 120 to that shown in Figure1 and includes a glass envelope 35 having its lower end closed by ametal cap 36 constructed of non-porous metal substantially unaifected bymercury or constructed of a metal having a non porous coatingsubstantially 125 unaifected by mercury. The cap 38 has its flange 37fused and sealed to the lower end of the glass envelope 35 over asubstantial area by the method fully set out in the Hotchkissapplication above referred to. A flexible element which may be a 180bellows 38 is provided and has a flange 39 fused and sealed to the upperend of the glass envelope 35. The end plate of the bellows carries amovable electrode 40 co-operable with a body of mercury designated at 41and contained in the 135 lower end of the envelope 35 and in directcontact with the cap 36. It will now be appreciated that the switch ofFigure 3 is identical with that shown in Figure 1 except that the trapon the electrode is omitted and that a different method 140 is utilizedfor closing the lower end of the glass envelope. Figure 3 alsoillustrates how the flange or sleeve between the bellows and glassenvelope may be formed integral with the envelope. Any suitableoperating mechanism my be provided for the bellows 38 to cause it toexpand and contract and move the electrode 40 into and out of contactwith the body of mercury 41. The cap 36 always contacts with the mercuryand serves not only as a closure but also as an electrode and makes itunnecessary to use lead in wires.

In all embodiments of the invention the switch is sensitive thoughpositive in its operation. Even where a mercury to mercury make andbreak is bad the flexible element is not'loaded with a heavy column ofmercury but carries only the small amount of mercury in the trap. Anddue to the positive fastening. of the rod type or solid type ofelectrode to the flexible element the movable electrode is positivelymoved in both directions either when oscillated or reciprocated.

From the foregoing it will be appreciated that in all embodiments of theinvention the flexible element is utilized without impairing orrendering diflicult the hermetic sealing of the container. In otherwords, by fusing and sealing the flexible element to the glass orplastic envelope the necessity of employing mechanical packing isavoided and a permanent and true seal is had. This permits the containerto be evacuated and if desired filled with an arc suppressing gas andyet the circuit making and breaking means may be operated from theexterior by a positive mechanical means and with the container in aflxed position.

Another important advantage resides in the organization by which themovable electrode is positively moved to both of its positions. Thisfollows from the positive connection or fastening of the electrode tothe flexible element and from the use of one electrode of the rod orsolid type as distinguished from a liquid or mercury electrode. And yetwith a movable electrode oi. this character the switch may have amercury to mercury make and break without loading the flexible elementwith a heavy column of mercury as the movable electrode may be equippedwith a trap as described.

I claim:

A mercury switch comprising a sealed envelope including a cup portion, abody of mercury in said cup portion, a sylphon bellows sealed to a wallor said envelope, a stationary electrode sealed to a wall of saidenvelope and immersed in the mercury I electrode to dip into saidmercury to make con-r tact between said electrodes through the mercury,and to move the electrodes with respect to each other to still furtherreduce the fluid path between the electrodes.

PAUL K. CRAMBLET.

